/*
 * Original Author -> Harry Yang (taketoday@foxmail.com) https://taketoday.cn
 * Copyright © TODAY & 2017 - 2022 All Rights Reserved.
 *
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see [http://www.gnu.org/licenses/]
 */

package cn.taketoday.aop.aspectj;

import org.aspectj.weaver.ReferenceType;
import org.aspectj.weaver.ReferenceTypeDelegate;
import org.aspectj.weaver.ResolvedType;
import org.aspectj.weaver.ast.And;
import org.aspectj.weaver.ast.Call;
import org.aspectj.weaver.ast.FieldGetCall;
import org.aspectj.weaver.ast.HasAnnotation;
import org.aspectj.weaver.ast.ITestVisitor;
import org.aspectj.weaver.ast.Instanceof;
import org.aspectj.weaver.ast.Literal;
import org.aspectj.weaver.ast.Not;
import org.aspectj.weaver.ast.Or;
import org.aspectj.weaver.ast.Test;
import org.aspectj.weaver.internal.tools.MatchingContextBasedTest;
import org.aspectj.weaver.reflect.ReflectionBasedReferenceTypeDelegate;
import org.aspectj.weaver.reflect.ReflectionVar;
import org.aspectj.weaver.reflect.ShadowMatchImpl;
import org.aspectj.weaver.tools.ShadowMatch;

import java.lang.reflect.Field;

import cn.taketoday.lang.Nullable;
import cn.taketoday.util.ClassUtils;
import cn.taketoday.util.ReflectionUtils;

/**
 * This class encapsulates some AspectJ internal knowledge that should be
 * pushed back into the AspectJ project in a future release.
 *
 * <p>It relies on implementation specific knowledge in AspectJ to break
 * encapsulation and do something AspectJ was not designed to do: query
 * the types of runtime tests that will be performed. The code here should
 * migrate to {@code ShadowMatch.getVariablesInvolvedInRuntimeTest()}
 * or some similar operation.
 *
 * <p>See <a href="https://bugs.eclipse.org/bugs/show_bug.cgi?id=151593">Bug 151593</a>
 *
 * @author Adrian Colyer
 * @author Ramnivas Laddad
 * @since 4.0
 */
class RuntimeTestWalker {

  private static final Field residualTestField;

  private static final Field varTypeField;

  private static final Field myClassField;

  static {
    try {
      residualTestField = ShadowMatchImpl.class.getDeclaredField("residualTest");
      varTypeField = ReflectionVar.class.getDeclaredField("varType");
      myClassField = ReflectionBasedReferenceTypeDelegate.class.getDeclaredField("myClass");
    }
    catch (NoSuchFieldException ex) {
      throw new IllegalStateException("The version of aspectjtools.jar / aspectjweaver.jar " +
              "on the classpath is incompatible with this version of Framework: " + ex);
    }
  }

  @Nullable
  private final Test runtimeTest;

  public RuntimeTestWalker(ShadowMatch shadowMatch) {
    try {
      ReflectionUtils.makeAccessible(residualTestField);
      this.runtimeTest = (Test) residualTestField.get(shadowMatch);
    }
    catch (IllegalAccessException ex) {
      throw new IllegalStateException(ex);
    }
  }

  /**
   * If the test uses any of the this, target, at_this, at_target, and at_annotation vars,
   * then it tests subtype sensitive vars.
   */
  public boolean testsSubtypeSensitiveVars() {
    return (this.runtimeTest != null &&
            new SubtypeSensitiveVarTypeTestVisitor().testsSubtypeSensitiveVars(this.runtimeTest));
  }

  public boolean testThisInstanceOfResidue(Class<?> thisClass) {
    return (this.runtimeTest != null &&
            new ThisInstanceOfResidueTestVisitor(thisClass).thisInstanceOfMatches(this.runtimeTest));
  }

  public boolean testTargetInstanceOfResidue(Class<?> targetClass) {
    return (this.runtimeTest != null &&
            new TargetInstanceOfResidueTestVisitor(targetClass).targetInstanceOfMatches(this.runtimeTest));
  }

  private static class TestVisitorAdapter implements ITestVisitor {

    protected static final int THIS_VAR = 0;
    protected static final int TARGET_VAR = 1;
    protected static final int AT_THIS_VAR = 3;
    protected static final int AT_TARGET_VAR = 4;
    protected static final int AT_ANNOTATION_VAR = 8;

    @Override
    public void visit(And e) {
      e.getLeft().accept(this);
      e.getRight().accept(this);
    }

    @Override
    public void visit(Or e) {
      e.getLeft().accept(this);
      e.getRight().accept(this);
    }

    @Override
    public void visit(Not e) {
      e.getBody().accept(this);
    }

    @Override
    public void visit(Instanceof i) {
    }

    @Override
    public void visit(Literal literal) {
    }

    @Override
    public void visit(Call call) {
    }

    @Override
    public void visit(FieldGetCall fieldGetCall) {
    }

    @Override
    public void visit(HasAnnotation hasAnnotation) {
    }

    @Override
    public void visit(MatchingContextBasedTest matchingContextTest) {
    }

    protected int getVarType(ReflectionVar v) {
      try {
        ReflectionUtils.makeAccessible(varTypeField);
        return (Integer) varTypeField.get(v);
      }
      catch (IllegalAccessException ex) {
        throw new IllegalStateException(ex);
      }
    }
  }

  private abstract static class InstanceOfResidueTestVisitor extends TestVisitorAdapter {

    private final Class<?> matchClass;

    private boolean matches;

    private final int matchVarType;

    public InstanceOfResidueTestVisitor(Class<?> matchClass, boolean defaultMatches, int matchVarType) {
      this.matchClass = matchClass;
      this.matches = defaultMatches;
      this.matchVarType = matchVarType;
    }

    public boolean instanceOfMatches(Test test) {
      test.accept(this);
      return this.matches;
    }

    @Override
    public void visit(Instanceof i) {
      int varType = getVarType((ReflectionVar) i.getVar());
      if (varType != this.matchVarType) {
        return;
      }
      Class<?> typeClass = null;
      ResolvedType type = (ResolvedType) i.getType();
      if (type instanceof ReferenceType) {
        ReferenceTypeDelegate delegate = ((ReferenceType) type).getDelegate();
        if (delegate instanceof ReflectionBasedReferenceTypeDelegate) {
          try {
            ReflectionUtils.makeAccessible(myClassField);
            typeClass = (Class<?>) myClassField.get(delegate);
          }
          catch (IllegalAccessException ex) {
            throw new IllegalStateException(ex);
          }
        }
      }
      try {
        // Don't use ResolvedType.isAssignableFrom() as it won't be aware of (Framework) mixins
        if (typeClass == null) {
          typeClass = ClassUtils.forName(type.getName(), this.matchClass.getClassLoader());
        }
        this.matches = typeClass.isAssignableFrom(this.matchClass);
      }
      catch (ClassNotFoundException ex) {
        this.matches = false;
      }
    }
  }

  /**
   * Check if residue of target(TYPE) kind. See SPR-3783 for more details.
   */
  private static class TargetInstanceOfResidueTestVisitor extends InstanceOfResidueTestVisitor {

    public TargetInstanceOfResidueTestVisitor(Class<?> targetClass) {
      super(targetClass, false, TARGET_VAR);
    }

    public boolean targetInstanceOfMatches(Test test) {
      return instanceOfMatches(test);
    }
  }

  /**
   * Check if residue of this(TYPE) kind. See SPR-2979 for more details.
   */
  private static class ThisInstanceOfResidueTestVisitor extends InstanceOfResidueTestVisitor {

    public ThisInstanceOfResidueTestVisitor(Class<?> thisClass) {
      super(thisClass, true, THIS_VAR);
    }

    // TODO: Optimization: Process only if this() specifies a type and not an identifier.
    public boolean thisInstanceOfMatches(Test test) {
      return instanceOfMatches(test);
    }
  }

  private static class SubtypeSensitiveVarTypeTestVisitor extends TestVisitorAdapter {

    private final Object thisObj = new Object();

    private final Object targetObj = new Object();

    private final Object[] argsObjs = new Object[0];

    private boolean testsSubtypeSensitiveVars = false;

    public boolean testsSubtypeSensitiveVars(Test aTest) {
      aTest.accept(this);
      return this.testsSubtypeSensitiveVars;
    }

    @Override
    public void visit(Instanceof i) {
      ReflectionVar v = (ReflectionVar) i.getVar();
      Object varUnderTest = v.getBindingAtJoinPoint(this.thisObj, this.targetObj, this.argsObjs);
      if (varUnderTest == this.thisObj || varUnderTest == this.targetObj) {
        this.testsSubtypeSensitiveVars = true;
      }
    }

    @Override
    public void visit(HasAnnotation hasAnn) {
      // If you thought things were bad before, now we sink to new levels of horror...
      ReflectionVar v = (ReflectionVar) hasAnn.getVar();
      int varType = getVarType(v);
      if (varType == AT_THIS_VAR || varType == AT_TARGET_VAR || varType == AT_ANNOTATION_VAR) {
        this.testsSubtypeSensitiveVars = true;
      }
    }
  }

}
